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Notice of GPS week number rollover on GPS Navigator / Sensor

To All Customers:

We greatly appreciate your use of our products.

This is to inform you of the “GPS week number rollover” problem and how it affects our GPS Navigator / Sensor.

The GPS system calculates time by counting the number of weeks up to a maximum of 1,023 weeks. After week 1,023, the week number count is reset to zero. This is called “GPS week number rollover”.

The GPS week number rollover occurs every 1,024 weeks - about once every 19.6 years. Therefore, when 19.6 years has passed from the reference date in the systems, the clock time incorporated in GPS sensors and navigators will be reset, causing as a result errors in display or output of date, or unstable occurrence in positioning operation.

When GPS week number rollover occurs, our GPS Navigator / Sensor may cause the following problems:

  1. Date displayed dates back to 19.6 years ago.
  2. All dated data output by equipment date back to 19.6 years ago.
  3. Due to this inaccurate date, positioning operation may temporarily become unstable or be interrupted.

When this rollover has occurred, please switch on the equipment twice to recover the normal positioning operation. After recovery of the operation, the date will remain as it is in 19.6 years ago, but time and positioning operation will function normally.

We regret any inconvenience this may cause you, but appreciate your kind understanding in this matter.

Sincerely yours,

Affected GPS Navigator / Sensor and Countermeasures

  • When the dated data displayed on equipment and the dated data output from equipment are not used, there would be no need to take countermeasures. When data is continued to be used, either one of the following countermeasures shall be taken:
    1. Upgrade of software version.
    2. Replacement of equipment (When equipment can not be dealt with by upgrade of software version).

Please refer to the tables below for countermeasures for each type of equipment.

It is possible to postpone the occurrence of rollover to the year of 2028 by upgrading of software, but it may not be possible to upgrade software, even if charge is paid, as the needed ROM software may not be available on all models. In such cases, replacement of equipment will be provided with charge. Please contact our distributors / dealers where you have purchased or our marine sales department for details on the equipment subject “upgrading of software version”. We appreciate your kind understanding that the cost shall be born by you for either case of the countermeasure above mentioned.

  • Even on the same equipment models, this phenomenon may occur on a different date, due to its software number and version number. The tables below list the earliest possible date of occurrences.

Table 1 - GPS Sensors / GPS Compass

Date of
rollover occurrence
Model Name Countermeasures
15-Aug-10 GPS-4A Unit replacement is necessary
15-Aug-10 GPS-5 Unit replacement is necessary
5-Feb-12 GPS-4Amk2 Unit replacement is necessary
5-Feb-12 GPS-6 Unit replacement is necessary
20-Jan-13 GPS-10 Unit replacement is necessary
20-Jan-13 GPS-10A Unit replacement is necessary
20-Jan-13 KBG-1 Upgrading of software
20-Jan-13 KBG-2 / DGPS-11 Upgrading of software
1-Aug-21 GPS-20A Serial No.02097323 and before::
    Unit Change GPS module
    Serial No.02097324 to .02097358 
    Upgrading of GPS module software
1-Aug-21 KBG-3 Serial No.00302555 and before::
    Unit Change GPS module
    Serial No.00302556 to 00302682
    Upgrading of GPS module software
19-Feb-23 KGC-1 Serial No.00101312 and before
    Upgrading of software
15-Aug-27 KGC-1 Serial No.00101313 to .00101791 
    Upgrading of software
1-Apr-29 KGC-1 Serial No.00101792 and after
    Upgrading of software
2-Dec-29 GPS-20A Serial No.02097359 and after
    Upgrading of GPS module software
2-Dec-29 KGB-3 Serial No.00302683 and after
    Upgrading of GPS module software

 

Table 2 - GPS Navigators

Date of
rollover occurrence
Model Name Countermeasures
15-Aug-10 KGP-95 / GPS-7 Unit replacement is necessary
15-Aug-10 KGP-97 / GPS-8 Unit replacement is necessary
15-Aug-10 KGP-910 / 910A Unit replacement is necessary
  GPS-77P
15-Aug-10 KGP-911 / GPS-88P Unit replacement is necessary
15-Aug-10 KGP-930 Unit replacement is necessary
5-Feb-12 KGP-98 / 98D Unit replacement is necessary
  GPS-9 / 9D
5-Feb-12 KGP-931 Unit replacement is necessary
20-Jan-13 KGP-9 / HG-7 Unit replacement is necessary
20-Jan-13 KGP-912 / GPS-99P Unit replacement is necessary
20-Jan-13 KGP-913 / 913D Upgrading of software
20-Jan-13 GPS-90 / 90D Upgrading of software
20-Jan-13 KGP-931D Unit replacement is necessary
1-Aug-21 KGP-920 Serial No.92002298 and before
    Unit Change GPS module
    Serial No 92002299 to 92002415 
    Upgrading of GPS module software
1-Aug-21 KGP-913MkII Serial No.91332146 and before::
    Unit Change GPS module
    Serial No.91332147 to 91332250 
    Upgrading of GPS module software
2-Dec-29 KGP-920 Serial No.92002416 and after
    Upgrading of GPS module software
2-Dec-29 KGP-913MkII Serial No.91332251 and after
    Upgrading of GPS module software

 

Table 3 - Chart Plotters

Date of
rollover occurrence
Model Name Countermeasures
15-Aug-10 KGF-960 Unit replacement is necessary
15-Aug-10 GTD-07 Switch on the power supply twice
15-Aug-10 GTD-2000 Unit replacement is necessary
15-Aug-10 GTD-2020 Switch on the power supply twice
15-Aug-10 GTD-210 Unit replacement is necessary
15-Aug-10 GTD-2200 / 2200X Switch on the power supply twice
15-Aug-10 GTD-2210 Switch on the power supply twice
15-Aug-10 GTD-2400 Switch on the power supply twice
15-Aug-10 GTD-2410 Switch on the power supply twice
5-Feb-12 GTD-1100 Unit replacement is necessary
5-Feb-12 GTD-2010 Switch on the power supply twice
20-Jan-13 GTD-1200 Unit replacement is necessary

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